Friday, January 1, 2016

Slaying the 3-headed Monster: Weight cut, fatigue and dehydration.

In my last post I addressed the challenge of keeping key
metabolic hormones in check during your weight-cutting period. This blog segment
focuses on taking down your hidden competitor: Fatigue. And more specifically,
how dehydration empowers fatigue, pushing much of the progress and improvement
you’ve trained for completely out of reach.

Sport scientists define fatigue as a decrement in the force
output of a muscle. Psychologists see fatigue as a ‘sensation’ of
tiredness. And physiologists define fatigue as the failure of a specific
physiological system. Consider that exercise is terminated at exhaustion—and
not at a point of fatigue. It is widely accepted that fatigue is a safety
mechanism that has evolved to prevent injury or death by means of overreaching.
But regardless of how you define it, fatigue is something we all fight with;
and regardless of physical and mental preparation, fatigue will always be
present.

What causes fatigue?

There are many things that can cause fatigue, not the least
of which is engaging in a work event that is beyond your capacity. This
type of fatigue is caused by our body’s inability to deliver the necessary
oxygen or nutrients in the blood to the working muscles. This is why we
train: To increase that capacity. But even if we have trained to, and
have the ability to do the necessary work, other factors can creep in and block
our ability to accomplish our goals.
Hydration levels have a direct impact on the blood volume and contribute to
success and failure rates.

Researchers have identified fatigue mechanisms that
originate in the neuromuscular system. These seem to be protective
systems in the body that can originate as high as the brain in the central
nervous system. Research has shown that in some athletes this level of
fatigue can limit work output by up to 32%. Researchers are not clear on
all of the factors that contribute to this “central governor” fatigue model,
but some that have been clearly shown are an imbalance in electrolyte
concentrations, and the brain perception of a lack of fuel. The ability
to replace key electrolytes and, in-turn, draw water into the blood plasma, is
an important part of strategic rehydration.

Research suggests that sweeter isn’t necessarily better.
In fact, scientists have shown that just sensation of sweetness in the mouth—not
glucose itself—will dampen the fatigue effect. In various studies,
athletes were asked to “swish the fluid around in the mouth, then spit it out.”
Those athletes saw an increase in performance versus those who merely drank
water. Other studies using sugar have also shown that more is not really
“more.” Athletes consuming concentrations as low as 2% have had similar
exercise times to failure as those consuming 18% concentrations. In
another interesting study, athletes were given glucose through an IV; those
athletes saw no improvement in performance over water alone. This is an
area that needs more research, but for now, be confident that a little
sweetness goes a long way.

Our brains monitor hydration levels closely. Because the brain interprets
dehydration as stress, it triggers a drop in performance. Too much
dehydration triggers production of stress hormones. The brain will limit
the number of muscle fibers you can recruit. Remember, a drop in total body water causes a drop in
blood plasma volume, which limits the body’s ability to deliver nutrients to the
muscles. We see this in combat sports like boxing and wrestling
and it’s been documented in sports as diverse as triathlons. Many times
hydration is a consideration of safety. Dehydration can lead to
cramping, exhaustion and even death due to heat stroke. But long before
we get to the point of illness, dehydration is contributing to fatigue and
limiting performance. The takeaway: Be sure to harvest all the hard work
you’ve done leading up to your event by keeping the opponent of fatigue on the
bench. Stay hydrated!